As the thriller “Unforgettable” wends its way toward its not very thrilling climactic scene, we are forced to ask: Why do people keep making essentially the same “crazy ex-” movie over and over again?

This one has two accomplished stars, Rosario Dawson and Katherine Heigl, and Ms. Dawson, especially, does creditable work, but it doesn’t matter because the format is so numbingly familiar. Ms. Heigl, looking carved out of ice, plays Tessa, who has not been coping well with her divorce from David (Geoff Stults). When he develops a serious relationship with Julia (Ms. Dawson), Tessa sets a diabolical plot in motion.

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Trailer: ‘Unforgettable’

The setup may vary — sometimes it’s an unbalanced roommate, or a surrogate mother, or a sexy nanny who gets that homicidal look in the eye — but it’s the same three-cornered dynamic. Here, both the director (Denise Di Novi) and the writer (Christina Hodson) are women, yet that doesn’t translate into a reimagining of the tired formula. Tessa and David have a young daughter (Isabella Kai Rice) who becomes a pawn in the deadly game, and Julia is given a back story involving an abusive boyfriend, but the tale still plays out the same way these yarns always do.

That’s dismaying, because although this is a female-centered movie, the women’s roles are not exactly empowering. The formula demands that one character be bonkers and that the other not be smart enough to realize how unhinged her adversary is until it’s too late. It’s woman in jeopardy meets woman on the verge, a reductive brand of thriller from another decade, freshened here only with the addition of a plot element involving Facebook.